Stretch bag wrapping machine

ABSTRACT

A machine is provided for drawing a stretched plastic bag down over a load on a pallet, or the like, to provide a protective and supportive wrapping for the load. The machine comprises a frame having a shape and dimension to circumbscribe the load on the pallet. Upright horns are mounted at the corners of the frame, each of which is engaged by a spring-loaded motor-driven roller. One or more of the horns is movable inwardly so that a stretchable plastic bag may be placed upside-down over the horns. The spring-loaded rollers engaging the horns are then driven to draw the sides of the bag down over the horns between the rollers and the horns into a gathered, accordion-like collapsed condition around the perimeter of the frame. The frame is then hoisted in an appropriate hoist sub-assembly to an upper position, in which it extends over the load on the pallet. One or more of the horns is then moved outwardly to stretch the collapsed bag to a slightly larger cross section than that of the pallet and its load. The frame is then lowered down over the loaded pallet and, as the frame moves downwardly, the stretched plastic bag is peeled from between the corner horns and the respective springloaded rollers as it is drawn down over the load and the sides of the plastic bag contract inwardly to provide a tight wrapping for the load which protects the load and maintains it in a stable condition.

United States Patent [191 King [ Sept. 2, 1975 STRETCH BAG WRAPPING MACHINE Henry E. King, Rt. 1, Box 980, Escondido, Calif. 92025 [22] Filed: Aug. 19, 1974 [21] Appl. No.: 498,268

[76] Inventor:

[52] U.S. Cl. 53/184; 53/187; 53/261;

Primary Examiner-Travis S. McGehee Attorney, Agent, or Firm-Jessup & Beecher 57 ABSTRACT A machine is provided for drawing a stretched plastic bag down over a load on a pallet, or the like, to provide a protective and supportive wrapping for the load. The machine comprises a frame having a shape and dimension to circumbscribe the load on the pallet. Upright horns are mounted at the corners of the frame, each of which is engaged by a spring-loaded motor-driven roller. One or more of the horns is movable inwardly so that a stretchable plastic bag may be placed upside-down over the horns. The spring-loaded rollers engaging the horns are then driven to draw the sides of the bag down over the horns between the rollers and the horns into a gathered, accordion-like collapsed condition around the perimeter of the frame. The frame is then hoisted in an appropriate hoist subassembly to an upper position, in which it extends over the load on the pallet. One or more of the horns is then moved outwardly to stretch the collapsed bag to a slightly larger cross section than that of the pallet and its load. The frame is then lowered down over the loaded pallet and, as the frame moves downwardly, the stretched plastic bag is peeled from between the comer horns and the respective spring-loaded rollers as it is drawn down over the load and the sides of the plastic bag contract inwardly to provide a tight wrapping for the load which protects the load and maintains it in a stable condition.

6 Claims, 2 Drawing Figures LL m . STRETCH BAG WRAPPING MACHINE 2 BACKGROUND 'OF'THE INVENTION So-called shrink wrapping techniques are in extensive present-day use for providing tensioned wrappings for collated or individual products. This technique in volves wrapping the individual or collated packages with a skin of drum-tight shrinkable film formed of pol yvinyl chloride plastic, or its equivalent.

However, the prior art shrink film processes involve complicated and expensive machines, which include energy-consuming heat tunnels, to effectuate the physical shrinkage of the film. The same result is achieved by the simple assembly of the present invention, without any need for heat, or any other energy source, to shrink the wrapping, and by the simple expedient of pulling a stretchable plastic bag down over the load in a stretched condition to provide a tight protective and supportive wrapping for the load.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation ofa mechanism suitable for carrying out the concepts of the invention; and

FIG. 2 is a perspective view ofa frame element which is incorporated into the mechanism of FIG. 1.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT The machine shown in the drawing is intended to wrap a load of stacked boxes, designated which, for example, are supported on a pellet 12. The purpose of the machine is to draw a resilient plastic bag 14 down over the load, in a stretched condition, and in such a manner, that the bag shrinks to form a tight protective and supportive wrapping for the load. The mechanism of the invention, in its illustrated embodiment. includes a rectangular frame 18 which is supported on four posts, such as the posts 20, by means of a plurality of annular bearings 22. The frame 18 is movable up the posts 20 to an upper position above the load 10, and down the posts so that the frame moves down surrounding the load to a lower position in which it circumscribes the pallet 12.

Transverse brace members 24 are provided at the top of the posts 20 to form a rectangular structure, and an electric motor 26 is mounted on top of the structure. The motor 26 is mechanically coupled to the frame 18 by appropriate chains 30, or other appropriate means, so that the motor may be energized to drive the frame between its upper and lower position on the posts 20. As shown in FIG. 1, the chain 30 is supported on appropriate idler pulleys 32 mounted on the brace 24. A similar chain may be supported on similar idler pulleys on the rear side of the assembly, to be driven by the same, or a second motor.

As best shown in FIG. 2, the frame 18 in the illustrated embodiment has a rectangular configuration. Four horns 50, in the form of elongated angle members, are mounted at the four corners of the rectangular frame. One or more of the horns S0 is movable between an outer position shown in the solid lines in FIG. 2, and an inner position shown by the broken lines. In the particular exampe of FIG. 2, two of the horns S0 at the right-hand side of the assembly are shown as movable between respective inner and outer positions, while the two horns at the left'hand side of the assembly are fixed.

The movable horns 50 on the right-hand side of the assembly are driven between their inner and outer position by means, for example, of an electric motor 52.-

The electric motor being Coupled to appropriate lead screws 54, which it turns in one direction or the other to move the particular thorns 50 inwardly and outwardly. Each of the horns 50 has aspring-biased roller 58 mounted adjacent its outer edge, and each springbiased roller 58 is driven by aseparate electric motor, only one of which is shown, and is designated 60.

In the operation of the machine, the righthand horns 50 are moved to their inner positions by the motor 52, and a resilient plastic'bag '14 is placed upside-down over the horns, while the bag is in its relaxed condition. The sides of the bag are then drawn down between the outer edges of the horns and the adjacent spring-biased rollers 58. The rollers 58 are then turned by their associated motors 60 to pull the sides of the plastic bag 50 down between the rollers and the adjacent horns so that the bag extends around the perimeter of the frame with its sides in a collapsed, accordion-like condition.

The frame is then moved to its upper position above the load 10, and the motor 52 is energized to move the right-hand horns outwardly so as to tension the collapsed bag, and to cause it to stretch. In this condition. the cross section of the bag is slightly larger than the cross section of the load 10. Then, the frame 118 is lowered down over the load, and as it passes down the sides of the load, the plastic bag 14 is peeled off from the horns 50, and it shrinks tightly about the load, as the frame proceeds downwardly. When the frame reaches the lower end of its travel, the entire bag is released, and forms a tight cover around the load to protect the load, and to form a support for the load on the pallet 12.

It will be appreciated that the mechanism of the invention is simple and reliable in its operation, and does not require any heat source in order to provide the desired shrinkage for the protective plastic cover. It will ,also be appreciated that although a particular cmbodi ment of the invention has been shown and described, modifications may be made. It is intended in the claims to cover the modifications that come within the spirit and scope of the invention.

What is claimed is:

ll. A stretch-bag mechanism for drawing a resilient plastic bag in a stretched condition down over a load and for releasing the bag so that it provides a tight, ten sioned wrapping for the load, said mechanism including: a frame having an inner dimension of a shape and size to fit over the load in a circumscribing relationship therewith; a hoist assembly coupled to the frame for raising the frame to an upper position and to lower the frame to a lower position down over the load; a plurality of upright horn members attached to the frame for receiving the sides of the resilient plastic bag as it is placed in an inverted position over the frame, at least one of said horn members being moveable inwardly with respect to the frame to permit the horn members to receive the bag in a relaxed condition, and being movable outwardly for causing the horn members to exert a lateral stretching force on the bag; first drive means coupled to said one of said horn members for moving the same inwardly and outwardly; spring-biased roller means mounted on respective ones of said horn members for engaging the outer surface of the bag as the sides of the bag are drawn down over the horn members and between the horn members and the corresponding roller means to cause the roller means to press the sides of the bag against the horn members; and second drive means mechanically coupled to the roller means to cause the roller means to turn and gather the bag between the horns and the roller means into an accordion-like configuration about the frame while the bag is in a relaxed condition, so that the bag may be subsequently stretched outwardly by movement of said one of said horn members and peeled over the load as the frame is lowered by the hoist assembly.

2. The combination defined in claim 1, in which said frame has a rectangular cross sectional shape.

3. The combination defined in claim 2, and which inmoving the same inwardly and outwardly. 

1. A stretch-bag mechanism for drawing a resilient plastic bag in a stretched condition down over a load and for releasing the bag so that it provides a tight, tensioned wrapping for the load, said mechanism including: a frame having an inner dimension of a shape and size to fit over the load in a circumscribing relationship therewith; a hoist assembly coupled to the frame for raising the frame to an upper position and to lower the frame to a lower position down over the load; a plurality of upright horn members attached to the frame for receiving the sides of the resilient plastic bag as it is placed in an inverted position over the frame, at least one of said horn members being moveable inwardly with respect to the frame to permit the horn members to receive the bag in a relaxed condition, and being movable outwardly for causing the horn members to exert a lateral stretching force on the bag; first drive means coupled to said one of said horn members for moving the same inwardly and outwardly; spring-biased roller means mounted on respective ones of said horn members for engaging the outer surface of the bag as the sides of the bag are drawn down over the horn members and between the horn members and the corresponding roller means to cause the roller means to press the sides of the bag against the horn members; and second drive means mechanically coupled to the roller means to cause the roller means to turn and gather the bag between the horns and the roller means into an accordion-like configuration about the frame while the bag is in a relaxed condition, so that the bag may be subsequently stretched outwardly by movement of said one of said horn members and peeled over the load as the frame is lowered by the hoist assembly.
 2. The combination defined in claim 1, in which said frame has a rectangular cross sectional shape.
 3. The combination defined in claim 2, and which includes four of said upright horn members respectively positioned at the corners of the frame.
 4. The combination defined in claim 1, in which said first drive means includes at least one electric motor.
 5. The combination defined in claim 1, in which said second drive means includes a separate electric motor coupled to each of the spring-biased roller means.
 6. The combination defined in claim 1, and in which a plurality of said upright horn members are movable inwardly and outwardly, and in which said first drive means is coupled to said plurality of horn members for moving the same inwardly and outwardly. 